JMIR Publications

ABSTRACT

Background:

The Carrot Rewards app was developed as part of a public-private partnership to reward Canadians with loyalty points (eg, for movies and groceries) for downloading the app, referring friends, completing educational health quizzes (“micro-learning”), and for health-related behaviors (eg, taking more steps) with long term objectives of increasing health knowledge and encouraging healthy behaviors. During the first three months after program roll-out in British Columbia, where the app was first launched, a number of program design elements were adjusted, creating natural experimental conditions with respect to the impact of several program features on user engagement levels.

Objective:

The main objective of this study was to examine the impact of reducing reward size over time, with secondary objectives of exploring the influence of other program design features such as reward timing, health intervention content (eg, diet, exercise), and type of reward program (eg, gas, travel, movies) on user engagement with an mHealth app.

Methods:

Participants in this longitudinal observational study included BC citizens downloading the app between March and May 2016. Regression methodology was used to examine the impact of several program design features on quiz offer acceptance and engagement with this mHealth app.

Results:

Our results, based on the longitudinal app usage of 54,917 users (Mean age= 35; % Female= 65%) indicated that the key drivers of user engagement and retention, in order of greatest to least impact, were: (1) the type of rewards earned by users (eg, movies, travel and grocery relative to gas); (2) time delay between offers; (3) the content of the health intervention (eg, healthy eating v. exercise); and (4) changes in the number of points offered. Our results demonstrate that reducing the number of points associated with a particular quiz by 10% only led to a 1-1.7% decrease in the likelihood of offer response, and that each of the other design features had larger impacts on participant retention than did changes in the number of points.

Conclusions:

The results of this study demonstrate that this program, built around an ongoing stream of a small number of reward points awarded instantly upon completion of health interventions, was able to drive significantly higher engagement levels than those demonstrated in previous literature exploring the intersection of mHealth apps and financial incentive. Further, this study suggests that, although the presence of an incentive matters to user engagement, the quantity of points offered for these reward point-based health interventions is less important than other program design features such as the type of reward points being offered, the timing of intervention and reward offers, and the content of the health interventions in driving continued engagement by users.